diff -r 000000000000 -r 6474c204b198 netwerk/base/src/nsTemporaryFileInputStream.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/netwerk/base/src/nsTemporaryFileInputStream.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTemporaryFileInputStream.h"
+#include "nsStreamUtils.h"
+#include <algorithm>
+
+NS_IMPL_ISUPPORTS(nsTemporaryFileInputStream, nsIInputStream)
+
+nsTemporaryFileInputStream::nsTemporaryFileInputStream(FileDescOwner* aFileDescOwner, uint64_t aStartPos, uint64_t aEndPos)
+  : mFileDescOwner(aFileDescOwner),
+    mStartPos(aStartPos),
+    mEndPos(aEndPos),
+    mClosed(false)
+{ 
+  NS_ASSERTION(aStartPos <= aEndPos, "StartPos should less equal than EndPos!");
+}
+
+NS_IMETHODIMP
+nsTemporaryFileInputStream::Close()
+{
+  mClosed = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTemporaryFileInputStream::Available(uint64_t * bytesAvailable)
+{
+  if (mClosed)
+    return NS_BASE_STREAM_CLOSED;
+
+  NS_ASSERTION(mStartPos <= mEndPos, "StartPos should less equal than EndPos!");
+
+  *bytesAvailable = mEndPos - mStartPos;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTemporaryFileInputStream::Read(char* buffer, uint32_t count, uint32_t* bytesRead)
+{
+  return ReadSegments(NS_CopySegmentToBuffer, buffer, count, bytesRead);
+}
+
+NS_IMETHODIMP
+nsTemporaryFileInputStream::ReadSegments(nsWriteSegmentFun writer,
+                                         void *            closure,
+                                         uint32_t          count,
+                                         uint32_t *        result)
+{
+  NS_ASSERTION(result, "null ptr");
+  NS_ASSERTION(mStartPos <= mEndPos, "bad stream state");
+  *result = 0;
+
+  if (mClosed) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  mozilla::MutexAutoLock lock(mFileDescOwner->FileMutex());
+  PR_Seek64(mFileDescOwner->mFD, mStartPos, PR_SEEK_SET);
+
+  count = std::min(count, uint32_t(mEndPos - mStartPos));
+  uint32_t remainBufCount = count;
+
+  char buf[4096];
+  while (remainBufCount > 0) {
+    uint32_t bufCount = std::min(remainBufCount, (uint32_t)sizeof(buf));
+    int32_t read_result = PR_Read(mFileDescOwner->mFD, buf, bufCount);
+    if (read_result < 0) {
+      return NS_ErrorAccordingToNSPR();
+    }
+    uint32_t write_result = 0;
+    nsresult rv = writer(this, closure, buf,
+                         count - remainBufCount, bufCount, &write_result);
+    remainBufCount -= bufCount;
+    if (NS_SUCCEEDED(rv)) {
+      NS_ASSERTION(write_result <= bufCount,
+                   "writer should not write more than we asked it to write");
+    }
+    mStartPos += bufCount;
+  }
+  *result = count;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsTemporaryFileInputStream::IsNonBlocking(bool * nonBlocking)
+{
+  *nonBlocking = false;
+  return NS_OK;
+}
+